Written by Slawomir (“Swavak”) Gromadzki, MPH

Quercetin is a flavonoid (plant pigment) commonly found especially in onions, apples and citrus fruits.

It is a potent antioxidant that fights against free radicals. Quercetin can reduce cortisol release during times of extended stress. It improves blood circulation, promotes normal blood pressure and protects against LDL cholesterol oxidation.

Few studies also demonstrated Quercetin improves metabolism helping to control body weight and may have potent anticancer properties with regards to prostate and colon cancer.

Quercetin, however, is commonly known especially due to its antihistamine properties. When our respiratory system is irritated, inflamed and swollen, it is the result of the release of histamine hormone, and since quercetin has an antihistamine affect it provides relief for those who experience common infection or allergy symptoms such as runny nose, inflammation and swelling.

According to a 2013 study Quercetin may have a bronchial dilating effect by reducing the release of proteins which lead to swelling and airway narrowing.

Large amounts may interact with blood thinners, corticosteroids, and aspirin.

Quercetin will be a good candidate for the supplement on the management and treatment of allergic diseases >


Weng Z, Zhang B, Asadi S, Sismanopoulos N, Butcher A, Fu X, Katsarou-Katsari A, Antoniou C, Theoharides TC. Quercetin is more effective than cromolyn in blocking human mast cell cytokine release and inhibits contact dermatitis and photosensitivity in humans. PLoS One. 2012;7(3):e33805. doi: 10.1371/journal.pone.0033805. Epub 2012 Mar 28.

Townsend EA, Emala CW Sr. Quercetin acutely relaxes airway smooth muscle and potentiates-agonist induced relaxation via dual phosphodiesterase inhibition of PLC and PDE4. Am J Physiol Lung Cell Mol Physiol. 2013 Jul 19.

Chirumbolo S. The role of quercetin, flavonols and flavones in modulating inflammatory cell function. Inflamm Allergy Drug Targets. 2010 Sep;9(4):263-85.

Perez-Vizcaino F, Duarte J. Flavonols and cardiovascular disease. Mol Aspects Med. 2010 Dec;31(6):478-94. doi: 10.1016/j.mam.2010.09.002. Epub 2010 Sep 15.

Egert S, Bosy-Westphal A, Seiberl J, Kürbitz C, Settler U, Plachta-Danielzik S, Wagner AE, Frank J, Schrezenmeir J, Rimbach G, Wolffram S, Müller MJ. Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: a double-blinded, placebocontrolled cross-over study. Br J Nutr. 2009 Oct;102(7):1065-74. doi: 10.1017/S0007114509359127. Epub 2009 Apr 30.

Cheng LC, Li LA. Flavonoids exhibit diverse effects on CYP11B1 expression and cortisol synthesis. Toxicol Appl Pharmacol. 2012 Feb 1;258(3):343-50. doi: 10.1016/j.taap.2011.11.017. Epub 2011 Dec 8.

Wang G, Song L, Wang H, Xing N. Quercetin synergizes with 2-methoxyestradiol inhibiting cell growth and inducing apoptosis in human prostate cancer cells. Oncol Rep. 2013 Jul;30(1):357-63. doi: 10.3892/or.2013.2469. Epub 2013 May 15.



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